Burr hole – A small opening in the skull made with a drill to remove localized fluid collection inside the skull.

Carotid angioplasty – A procedure in which a balloon catheter is guided through blood vessels to the carotid artery to reduce blockage and improve blood flow.

Carotid arteries – The arteries in the neck that supply blood to the brain.

Carotid artery stenosis – (narrowing) A major risk factor for ischemic stroke. Narrowing of the arteries is usually caused by plaque in an artery. Plaque forms when cholesterol, fat and other fatty substances build up in the inner lining of an artery.